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Bell’s Palsy

Other Known Aliases – facial nerve palsy, cranial nerve VII palsy

Definition – paralysis of cranial nerve VII that can can effect both motor and sensory function

Clinical Significance – This condition affects up to 20 patients per 100,000 population with no gender, race, or geographic predilection. It is the most common cause of unilateral acute peripheral nerve palsies. Although benign in clinical course, providers must pay close attention to differentiate between Bell’s palsy and a supranuclear lesion (stroke). The most significant clinical difference between these two condition is the ability to raise the eyebrow and wrinkle the forehead.

History –Named after Sir Charles Bell (1774-1842), a Scottish surgeon, anatomist, physiologist, neurologist, and noted philosophical theologian who received his medical doctorate at the University of Edinburgh in 1799. While still a student, he illustrated and published an extraordinary textbook entitled “A System of Dissection Explaining the Anatomy of the Human Body” After graduation, he was admitted and enrolled at The Royal College of Surgeons where he proved himself to be as skilled in surgery as in anatomy. He further published two subsequent volumes of “Anatomy of the Human Body”, with his brother John (also a skilled anatomist and surgeon). He was such a prolific teacher and professor that the faculty at the University of Edinburgh blocked his advancement and he was forced to move to London where he first opened a private school of anatomy and then took over the Great Windmill Street School of Anatomy (founded by William and John Hunter). In 1811, he published “An Idea of a New Anatomy of the Brain” considered to be the quintessential textbook of neurology. In 1821, he published a paper entitled ” On The Nerves: Giving an Account of some Experiments on Their Structure and Functions, which lead to a new arrangement of the systems” where he described the trajectory of the facial nerve and the unilateral facial paralysis that could result. This paper is still considered one of the classics of neurology and led to the disease bearing his name. In 1824, he became the first professor of anatomy and surgery of the College of Surgeons in London and was knighted by King William IV due to his contributions of the advancement of medicine.

Huntington’s Disease

Other Known Aliases – Huntington’s chorea

Definition – Autosomal dominant condition caused by expansion of the cytosine-adenine-guanine (CAG) trinucleotide repeats in the HD gene located on short arm of chromosome 4p16.3 that encodes the protein huntingtin.

Clinical Significance – This condition affects 4-15 in 100,000 peoples of European descent and is extremely rare in non-European lineage. The classic manifestations of the disease include chorea, psychiatric illness, and dementia. These symptoms begin very slow and are often missed for a period of time, but always progress to severe deterioration of neuromuscular function. It is uncurable and treatment is directed towards support and planning of care. Average length of survival after symptoms onset is 10-20 years

History –Named after George Huntington (1850-1916), an American physician who received his medical doctorate from Columbia University in 1871 at the age of 21. He came from a long line of physicians dating back to 1797, when his grandfather opened the family practice in East Hampton. He took meticulous notes on the disease that bears his name from going on house calls with his father early in his childhood, as well as reading and transcribing notes from his father and grandfather. He only published two papers in his career, the first of which was on this disease. He read this manuscript before the Meigs and Mason Academy of Medicine in Middleport, Ohio in 1872 (just 1 year after graduating medical school) and received such acclaim that it was published in the Medical and Surgical Reporter of Philadelphia just 2 months later. This paper was published in the German literature later that year and his name was forever attached to this disease. Even William Osler read and commented on this paper in 1908 saying ” In the history of medicine there are few instances in which a disease has been more accurately, more graphically, or more briefly described.”

There are six (6) segments of the nerve after it emerges from the pons of the brainstem:

Intracranial (cisternal)

Meatal (from brainstem to internal auditory canal)

Labyrinthine (internal auditory canal to geniculate ganglion)

Lacrimal gland, nasal/palate, pterygopalatine ganglion

Tympanic (geniculate ganglion to pyramidal eminence)

Stapedius nerve

Mastoid (pyramidal eminence to stylomastoid foramen)

Chorda tympani à tongue, salivary glands, lingual nerve

Extratemporal (stylomastoid foramen to post parotid branches)

5 major facial branches

Temporal

Zygomatic

Buccal

Mandibular

Cervical

Definition and Epidemiology

Bell’s Palsy is an acute peripheral nerve palsy of unknown etiology and makes up almost half of such cases. It is estimated that the annual incidence is around 20 patient per 100,000 population. There is no race, geographic, or gender correlation., though there is some old data on increased risk during 3rd trimester of pregnancy.

Pathogenesis

Had been hotly debated for many years as to the cause of this condition and is generally considered to be caused by Herpes Simplex virus due to associated serologic evidence in effected patients. Newer data has been published, but is not entirely conclusive. Most agree that is due to some viral pathogen with herpes being the most common, but also implicating CMV, EBV, adenovirus, and coxsackievirus. Specifically, the signs and symptoms are a result of viral mediated inflammatory demyelination of the nerve.

Signs and Symptoms

Most common presentation is acute (over several hours) unilateral facial paralysis with:

Motor

Inability to close the eye

Eyebrow sagging with inability to wrinkle the forehead

Obliteration of the nasolabial fold

Dropping of the affected corner of the mouth

Sensory

Hyperacusis

Loss of taste on the anterior 2/3rd of tongue

Symptoms are progressive and usually reach peak involvement within 3 weeks of onset. Patients should begin to have return of function within 2-4 months.

Diagnostic Studies

Bell’s palsy is a clinical diagnosis and diagnostic studies are generally not indicated unless the presentation is atypical, still progressing at 3 weeks, or there is no return of function by 4 months. History of facial twitching or spasms preceding the paralysis raises suspicion of compressive neuropathy from tumor or mass.

Electromyography (EMG)

The most simplest of the electrodiagnostic tests that can be used to show action potentials on active volition. Some degree of potential infers that the nerve is still intact and therefor, can improve.

Nerve Conduction Studies (NCS)

Supramaximal stimulation near the parotid gland with measured evoked potentials over the orbicularis oculi, nasalis, and lower facial muscles can measure the degree of axonal loss. Studies have shown >75% is the critical cutoff for low likelihood of full recovery. Ideally, this should be performed within 2 weeks of symptom onset for a more accurate prognosis.

Facial Nerve Stimulation

Should be considered with 2 weeks of symptoms onset if surgical decompression is considered due to potential for reversibility.

Needle EMG

Utilized after 3 weeks to assess the degree of axonal damage and evidence of subclinical reinnervation for recovery

Severity Grading

The House-Brackman scale is the most common grading scale that uses objective criteria to score the severity, mark progression, and track return of function.

Treatment

Mainstay of therapy for Bell’s palsy is corticosteroids (for the inflammation) and antivirals (for the viral pathogens). Current recommendations are:

Prednisone 60-80mg daily for 7 days

Valacyclovir 1000mg TID for 7 days

Within 72 hours of symptoms onset

Eye care should include artificial tears and an eye patch for sleeping.

Prognosis

Favorable prognosis if any recovery is seen within 21 days of symptom onset with data showing 71% with complete resolution, 13% with slight residual sequelae, and 16% with residual weakness, synkinesis, or contracture. 94% of patients with incomplete involvement have full resolution, while only 60% of complete involvement returned to normal function.

19yo male is brought into the emergency department by EMS after getting into an altercation and getting knocked unconscious. He unsure of how long he was out, but he came to once EMS arrived. He denies any nausea, vomiting, or vision changes. He is drowsy/lethargic with his eyes closed, but is arousable to voice. He can carry on a conversation, but he needs frequent redirection and he does not know where he is. While talking with him, the nurse starts an IV and he tries to swat her away with his opposite hand.

What is the classic score we use and what is his score?

The Glasgow Coma Scale (GCS) was first devised in 1974 and has been the predominant neurologic scoring system since. It takes into account 3 main variables and each variable has a point score attached to it. The maximum score is 15 and the minimum score is 3 (3T if intubated).

The GCS was never designed to be used for acute injury. It was created to monitor changes in neurologic status of patients in a neurosurgical unit and was not designed to have the 3 individual variables combined into one score. Here are the important limitations of the GCS.

The GCS is NOT reliable

It is made up of subjective elements that are open to the interpretation of each provider assessing the patient and has been repeated shown to have poor inter-rater reliability.

One study showed only a 38% accuracy between raters and were 2 or more points off 33% of the time.

Providers CAN’T remember the scale

It has too many elements and is regarded as too complicated to be easily, and rapidly applied to patients

In 2003, it was discovered that 25% of British hospitals were using the original 12-point scale instead of the current 13-point scale without anyone noticing.

The GCS is only GROSSLY predictive

It is not designed to predict outcomes of patients with acute neurologic injury.

The GCS is NOT equal to the sum of its parts

The original creators vehemently opposed the summed total score because it assumes that each variable is equal to the others in terms of importance

Example

GCS of 4 with 1E + 1V + 2M = 48% mortality

GCS of 4 with 1E + 2V + 1M = 27% mortality

GCS of 4 with 2E + 1V + 1M = 19% mortality

Are there any other scoring systems out there?

The motor subscale of the GCS has been proven to be most predictive of outcomes in patients with neurologic trauma and injury. This has led to debate about whether to do away with the other 2 subscales and use just the motor score (since it has been shown to close to linear in regards to survival).

Healy C. J Trauma. 2003.

But this is still 6 points and some argue can be further simplified. One study broke down the 6-point motor subscale and found that only 3 of those were statistically important. Those are:

Obeys commands

Localizes to pain

Withdrawal to pain or less

This new Simplified Motor Scale can be remembered by the acronym TROLL (Test Responsiveness: Obeys, Localizes, Less). 2 other simplified scores have also been created to help quickly determine neurologic status. These are:

AVPU

Alert

Responds to verbal stimuli

Responds to painful stimuli

Unresponsive

ACDU

Alert

Confused

Drowsy

Unresponsive

There is another, although more complicated, score called the FOUR score, which has 4 components and stands for Full Outline of UnResponsiveness. Unfortunately, it is even more complicated than the GCS (in the original study it was performed by neurologic specialists, not general practitioners) and it performed just as poorly in external validation studies as the GCS.

Wijdicks EF. Ann Neurol. 2005.

Bottom Line

GCS is essentially worthless clinically even when it is calculated correctly. Simplified scores give just as much information, are easier to use, and are just as predictive. But….you will always be asked “what is the patient’s GCS”, in spite of the growing evidence against it.

19yo male is brought into the emergency department by EMS after getting into an altercation and getting knocked unconscious. He unsure of how long he was out, but he came to once EMS arrived. He denies any nausea, vomiting, or vision changes. He is drowsy/lethargic with his eyes closed, but is arousable to voice. He can carry on a conversation, but he needs frequent redirection and he does not know where he is. While talking with him, the nurse starts an IV and he tries to swat her away with his opposite hand.